People are generally aware of the most common causes of hallucinations, like schizophrenia and a really high fever. But lesser known are the more rare causes; here are six you probably haven't heard about.

The ALS Ice bucket challenge has taken the internet by storm, spreading awareness of the progressive neurodegenerative disease and daring people to raise money toward its cure. With celebrities from Taylor Swift to former President George Bush completing the ALS Ice Bucket Challenge, it’s no surprise that the ALS Association reported the social media sensation had already raised $41 million.

Amyotrophic Lateral Sclerosis, commonly referred to as Lou Gehrig’s disease, is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord. As the neurons slowly die, they can no longer send messages to the muscles. This causes difficulties in movement, speech, swallowing, and even breathing. The vast majority of deaths from ALS are caused by respiratory failure, however, a small number of fatalities are caused by malnutrition as a result of troubles chewing and swallowing.

The ALS Ice Bucket Challenge was created by ALS patient Pete Frates and his friends. Frates, now 29, had been living with the condition since 2012. The rules are simple enough; if you get nominated for the challenge you have to dump a bucket of ice cold water over your head within 24 hours and donate to the ALS Association charity. The magic of twitter and the hashtag #IceBucketChallege, had attracted thousands to the cause. With the money raised by the challenge, the ALS Association announced they can fund 21 new ALS projects in addition to the 98 already active studies. This will certainly bring science significantly closer to the ultimate goal of a world without ALS.